When discussing weapons in science fiction, a plasma weapon is a type of raygun that fires a stream, bolt(s), pulse or toroid of plasma (i.e. very hot, very energetic excited matter). The primary damage mechanism of these fictional weapons is usually thermal transfer; it typically causes serious burns, and often immediate death of living creatures, and melts or evaporates other materials. In certain fiction, plasma weapons may also have a significant kinetic energy component, that is to say the ionized material is projected with sufficient momentum to cause some secondary impact damage in addition to causing high thermal damage. In some fictions, like Star Wars, plasma is highly effective against mechanical targets such as droids. The ionized gas disrupts their systems.

Fictional plasma weapons are often visually analogous to real-life plasma torches that cut into materials for industrial use purposes; however, said torches currently only produce a plasma jet of several inches at most.

Plasma weapons are often, especially in video games, depicted as very powerful, but short-ranged and/or less energy-efficient than other weapon types.

Artemis Fowl book series: Cannon-sized plasma weapons are featured, with Koboi Laboratory cannons set to kill, whereas those in Police Plaza are set to stun. To function, both need a reservoir of plasma, which reverts to an inert semi-liquid state when the guns are deactivated.

BattleTech has recently introduced two BattleMech-scale plasma weapons, the Clan Plasma Cannon, which only bathes the target in flaming gases, thus causing no damage in favor of massive waste heat to BattleMechs, though heavy damage to vehicles and infantry, and the Inner Sphere Plasma Rifle, which causes sizeable amount of damage in exchange for reduced waste heat. Both use lasers and a plastic foam which becomes a plasma when lased.

Blake's 7: Terran Federation pursuit ships and planetary interceptors are commonly equipped with "plasma bolts", which can home in on (and strike) a target faster than light with accuracy and precision. They project enough force to destroy most unprotected space-based objects and craft in a single strike. Smaller Federation military vessels may be armed with up to four plasma bolt hardpoints.

Robocraft has plasma Launchers that is practically an explosive projectile that gives massive damage to enemy players but short range.

Bolo: Bolos, the artificially intelligent superheavy tanks which are the protagonists of the series, use Hellbores, large fusion-initiated plasma cannons with a yield measured in megatons per second of fire.

In Crysis Warhead, the final mission features the "PAX Cannon" (Plasma Accumulator eXperimental Cannon), which is a devastatingly powerful hand-held rifle the player can then use to quickly destroy the attacking aliens. The power of the weapon rapidly drops with the distance the projectile travels, limiting it to short or medium range. It can destroy most vehicles with a single shot, and has unlimited ammo (presumably by using the atmosphere to generate plasma).

The Doom series features a rapid-fire plasma rifle, and the much more destructive BFG 9000.

The computer games Dune II, Dune 2000, and Emperor: Battle for Dune. The Harkonnen Devastator Tank is equipped with dual plasma cannons, which fire plasma "shots" over a short distances. They are powered by a nuclear reactor, which can be pushed into a meltdown under certain circumstances.

Earth 21X0 (Earth 2140, Earth 2150, Moon Project, Earth 2150: Lost Souls, Earth 2160) has plasma turrets for the UCS faction, stated by the manual to be reverse-engineered from a downed alien craft. Due to its high damage, high rate of fire and regenerating ammo, it is arguably one of the most powerful weapons.

Earthsiege 2 features a human-developed plasma cannon, whose blast can be powerful enough to destroy a fully shielded HERC with one shot though at the cost of leaving little salvageable material behind.

Eve OnlineMMORPG Large-scale plasma cannons and plasma railguns are the favored weapon of the Gallente Federation.

The Fallout series features a wide range of handheld plasma weaponry, ranging from one-handed pistols powered by small energy cells, to more conventionally shaped rifles and heavy weapons dubbed "plasma casters", both powered by "microfusion cells". These weapons produce green bolts that damage an opponent severely, and tend to reduce enemies to semi-liquid on death - in Fallout 3 and Fallout New Vegas, this is puddle of green goo, but in Fallout 1 and Fallout 2 the character's clothing and body can clearly be seen disintegrating and sloughing off its skeleton, which collapses shortly after. Judging by the protracted groan produced by such victims of plasma fire, this process is extremely painful.

F.E.A.R. series: The Type-7 Particle Weapon, a portable sniper weapon which fires a high velocity particle burst that vaporizes a human save for bone material.

The G-Police series included a plasma weapon for the player, it was to be charged first, before firing.

Freelancer, among a number of other starfighter-mounted energy weapons, plasma weapons have short range and low muzzle velocity but high damage as a trade-off. Pistols and rifles are also seen wielded by the main characters in certain cutscenes.

Half-Life 2: While never explicitly described as a "plasma rifle", the Overwatch Standard-Issue Pulse Rifle functions much like the plasma rifles of most FPS games. The main difference is that Pulse Rifles function by using containers filled with dark energy, as clips which expel this material in controlled bursts. They also can fire a compressed orb of dark energy as a form of self-propelled projectile. Dark energy has heat and kinetic damage, and due to the nature of this sort of exotic matter, it causes normal matter to vaporize and cease to exist. Similar weapons are found mounted on the game's enemy warships and vehicles.

The Halo series: used by the Covenant: they use magnetic coils to form, generally, spheres of plasma. They employ plasma in anything from pistols to ship-to-ship combat.

The Hammer's Slammers series: Powerguns use precicely arranged copper atoms stored in a plastic matrix. The atoms are pulled down the mirror-smooth barrel of the weapon by electromagnets. The barrels are cooled by liquid nitrogen and air, as most use a rotary assembly.

Metroid Prime Hunters features an extravagant weapon: The Judicator is said to be powered by cold-fusion synthesis and fires supercooled plasma, with temperatures close to absolute zero, and is capable of freezing the target at close ranges when used by Noxus.

Metroid Prime 3: Corruption: The Plasma Beam returns and is once again a heat-based weapon however it now has longer range, due to all beam-weapon upgrades being stacked, thus it has the range of Samus' standard power beam. Samus obtains the Plasma Beam upgrade by defeated the Phazon-corrupted bounty hunter Ghor and the beam features a wielding attactment that Samus can use to repair damaged circuit boards. Due to its heat-based nature it is lethal to mechical/robotic enemies and causes metal debris and ice to melt away. Later in the game, Samus obtains the Nova Beam upgrade which resembles Samus' traditional Plasma Beam from Super Metroid and Metroid Fusion mainly due to its green color and ability to penetrate armor.

Metroid: Other M - The Plasma Beam returns in its traditional form as a greenish color beam that can penetrate though most enemies and is Samus' final and most powerful beam upgrade. In the game, one of Samus' allies, GF Soldier Anthony Higgs carries a large plasma beam gun, but unlike Samus' Plasma beam it has to recharge in-between shots and according to Anthony it "takes forever to charge". Anthony uses his Plasma beam twice to save Samus from the clone of her nemesis Ridley. Both Samus' and Anthony's version of the Plasma Beam are shown to be highly effective at piercing Ridley's thick hide. Though Samus' starts the game already equipped with the Plasma Beam upgrade, she refrains from using it along with most of her abilities until its use is approved by Commander Adam Malkovich. It is unlocked just before the boss fight with Ridley.

MissionForce:CyberStorm, a turn-based game based on EarthSiege Hercs (battle robots). Plasma guns with short range but high power.

OGame: The Plasma Turret, one of the most advanced defense structures in the game fires an powerful ray of heated plasma using a nuclear reactor for energy. The Bomber is a powerful ship that fires plasma bombs and is very useful against light defense structures.

UFO Aftermath: Reticulans have plasma pistols as well as plasma rifles which actually operate like a grenade launcher. The reverse-engineered human version of the plasma pistol branches off into a proper plasma rifle and a short-range but very devastating plasma shotgun.

UFO: Alien Invasion:Aliens use plasma weaponry from the beginning of the game, which later gets replaced by particle beam weaponry. They are depicted as short to medium range weapons, firing blue projectiles. The ingame text explains that the plasma is encased in a thin layer of plastic which reduces the rate at which the plasma cools down and thus increases range. Upon retrieving the weapons from the battlefield, the player is given a new research option. After researching it, the weapons can be produced at the base and used by the player's troops.

Unreal series: the pulse/link guns and several vehicle-mounted weapons are plasma weapons. Also, the ASMD Shock Rifle's secondary fire is said to be a ball of seeded plasma whose EM field contains anti-photons; shooting the field with the photon beam of the primary fire causes the photons of the beam and the anti-photons of the ball to mutually annihilate each other in a violent explosion. This maneuver is officially known as a "shock combo" and is the second most powerful attack in the series while on foot.

Vendetta Online, the twitch-based space MMORPG, includes a variety of plasma weapons.

Warframe: In the open beta version, there are two craftable plasma shotguns with a unique held-trigger function. While holding the firing button, the plasma shotguns will add an additional pellet per following shot until it reaches a maximum of 10 pellets per shot, all while increasing its rate of fire and ammunition spent.

Warhammer 40,000, The Imperium of Man utilises plasma weapons in a great deal of different types, ranging from man-portable pistols and heavy rifles to huge Titan-mounted cannons, as do the forces of Chaos. While they are powerful weapons, the poorly understood technology of the gun occasionally suffers from severe overheating, which can often prove fatal to the wielder. Plasma rifles and cannons are also used by the Tau Empire and the Eldar, though their own technologies sacrifice a degree of firepower to avoid the overheating problem.

Wing Commander: a short-ranged but very damaging fighter weapon which uses extreme amounts of energy.

X-COM: nearly all alien weapons are plasma pistols/rifles/heavy plasmas. Alien craft use plasma weaponry as well. They work by superheating atmospheric gases in a small Elerium-powered reactor, thus creating plasma, then amplifying it with another Elerium crystal. After the projectile is ready, the gun fires it with an electromagnetic particle accelerator. This technology is reverse-engineered into the Gauss weapons in the Second Alien War because plasma weapons explode when fired underwater (not to mention that Elerium-115 becomes inert upon prolonged contact with seawater), hence why the aquatic aliens used sonic weaponry instead.